1. Field of the Invention
The present invention relates to a silver halide color photographic light-sensitive material, and more specifically, to a light-sensitive material having an improved push-processing suitability.
2. Description of the Related Art
A silver halide color photographic light-sensitive material generally has at least one silver halide emulsion layer on a support, each layer having its own color sensitivity (the term "color sensitivity" used here is defined as the characteristic for sensing any of the three regions in the visible spectrum ray, namely, red, green, and blue).
In the field of color photographic light-sensitive materials, especially of color reversal light-sensitive materials which are often used by professional photographers, high-sensitivity color light-sensitive materials are required in order for photographs of special scenes including sports events, which requires a quick shutter speed, or theatricals in which the amount of light is very much limited, and usually too small for a usual exposure. However, there are few types of color light-sensitive photographs which meet the requirement of such an extremely high sensitivity.
In consideration of the above situation, adjustment of the sensitivity is carried out through a process to compensate the lack of the exposure light amount. The adjustment of the sensitivity through the process is called "push-processing". In the case of the color reversal light-sensitive material, the process is carried out by making the time period of the first development (black and white development) longer than the standard processing time.
However, the conventional color reversal light sensitive material does not always have a sufficient push-processing suitability, but may be of the followings.
1. The type which cannot be sensitized unless the time period for the first development is made much longer than the standard processing time.
2. In the case of a light-sensitive material having a structure divided into high-sensitivity layers and low-sensitivity layers, a change in gradation may occur by the push-processing, because both layers are different in development processing suitability.
3. The type which involves a significant decrease in color image density when the degree of sensitization is raised by prolonging the time period of the first development.
4. The type which involves the degradation of the color balance in the push-processing, due to the difference in development processing suitability between the red-, green-, and blue-sensitive layers.
There has been a great demand for development of a technique which can solve the above-listed drawbacks, freely control the degree of sensitization, and causes no bad influence on the standard process.
The object of the present invention is to provide such a technique, and a color photograph light-sensitive material prepared by the technique.
JP-A-51-128528 (U.S. Pat. No. 4,082,553) ("JP-A" means Published Unexamined Japanese Patent Application) discloses a color reversal light-sensitive material having an improved interlayer effect, which comprise a silver halide emulsion layer in which silver halide grains, the surface of each of which is fogged, are scattered. However, the surface-fogged silver halide grains are distinguished from those having fog in the interiors (JP-A-51-128528, claim 11), and the addition of surface-fogged silver halide grains causes a bad influence to the photographic property on the standard process, and significantly decreases the color image density in the push-processing.
U.S. Pat. Nos. 2,996,382; 3,178,282 and 3,397,987 discloses a negative image-forming photographic element having high speed and contrast increased by adding both silver halide grains which can form a surface latent image when exposed, and silver halide grains having an internally fogged core. However, the specification of these documents makes no mention of push-processing or a regular color reversal light-sensitive material. Further, in the photographic element, a silver halide grain having a surface latent image releases a reaction product in accordance with the exposure amount, which creates a cleavage in a silver halide grain having an internally fogged core, thereby enabling the development. Consequently, the speed and contrast are increased even in the standard development, and the sensitization by the push-processing cannot be controlled.
Further, JP-B-46-19024 (U.S. Pat. No. 3,505,068) ("JP-B" means Published Examined Japanese Patent Application) discloses a method of effectively lowering the contrast in a color reversal light-sensitive material having each emulsion layers of the same light-sensitivity divided into a high-sensitive layer which uses silver iodide, and a low-sensitive layer which uses grains each obtained by covering the core of silver haloiodide with a silver-iodide-free silver halide shell. However, the core/shell type silver halide grain used here does not have an internally fogged core, show any special effect with regard to the push-processing.
JP-A-59-214852 discloses a technique of suppressing the change in gradation or the deterioration of color balance, and decreasing the lowering rate of the color image density in the push-processing, in which the silver halide emulsion having an internally fogged core is added to the silver halide emulsion layer or adjacent layers thereof so as to make the fogged core to function during the push-processing, advancing the development. In this technique, the sensitivity of the emulsion layer to which the silver halide emulsion having the internally fogged core increases in the push-processing, and therefore the color balance after the push-processing can be adjusted by adding the emulsion to the emulsion layer having a relatively low degree of sensitization.
In the case where the increase in sensitivity after the push-processing of a particular emulsion layer is extremely great, the rise of the sensitivity, in some cases, is insufficient even if the silver halide emulsion having the internally fogged core is added in great amount to the emulsion layer having a low degree of sensitization. In this case, a good color balance cannot be achieved after the push-processing, and further the color image density decreases due to the emulsion having the internally fogged core added in great amount.
Colloidal silver is known as an agent for enhancing the development activity of adjacent layers more than the above fogged emulsion. For example, JP-A-60-126652, JP-A-63-304252, JP-A-2-110539, JP-A-3-113438, JP-A-3-226732, and U.S. Pat. No. 979,001 discloses a light-sensitive material containing colloidal silver in its emulsion layer or adjacent layers thereof. Of these documents, U.S. Pat. No. 979,001, JP-A-60-126652, JP-A-63-304252, JP-A-2-110539, and JP-A-3-113438 are directed to improvement of the reproducibility of the image quality or gradation. Although JP-A-3-226732 covers the push-processing suitability also, this document makes no mention of yellow colloidal silver giving a high push-processing suitability, or addition of yellow colloidal silver to adjacent layers of each of layer having a color sensitivity.
As described above, there have never been studies of the influence of colloidal silver on improvement of the development activity, more specifically, there have never been researches on what type of colloidal silver, and how it should be added to a light-sensitive material for achieving a preferable push-processing suitability.